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The sympathetic nervous system plays a permissive, if not primary causal role in the genesis and maintenance of human essential hypertension. Excessive sympathetic nervous system activity in man is most apparent in early forms of hypertension (prehypertension and white-coat type). Renal nerves are of particular interest because of their roles in modulating the activity of the renin-angiotensin system and renal sodium excretion. Renal denervation substantially ameliorates the development of hypertension in animal models such as renovascular, spontaneously hypertensive, and steroid-induced hypertension in rats and aortic coarctation in dogs. In man, catheter ablation of renal nerves has been undertaken in the late phases of hypertension; in a rigorously controlled trial in resistant hypertension (SYMPLICITY HTN-3), renal denervation did not reduce blood pressure over the long term. Is this because renal denervation is more appropriate to prevent than treat late-stage hypertension? Are there anatomical or technical barriers yet to be overcome in the procedure? These and other issues are addressed by two experts in this issue of the controversies series: Deepak L. Bhatt and Murray Epstein. [ABSTRACT FROM AUTHOR]

It is widely believed that “high-ceiling” loop diuretics are required in patients with renal impairment and that “low-ceiling” thiazides are not sufficiently potent to cause meaningful natriuresis and diuresis. If this statement is true, at what level of renal function do thiazides lose their punch? Another related issue is the enlightened use of diuretic combinations. Use of diuretics in chronic kidney disease and hypertension has been addressed in the many guidelines, but further insight is provided in this installment of the “Controversies” series by two well-known authorities, William Elliott, M.D. Ph.D. and Rajiv Agarwal, M.D. [ABSTRACT FROM AUTHOR]

Age is the most powerful of risk factors and is related continuously to systolic BP and cardiovascular disease risk. Yet current guidelines have dichotomized age groups around a cutoff value of 55-60 years and some guidelines now suggest that age should affect diagnostic thresholds and drug choices. These choices are not supported directly by scientific evidence but are based on expert opinion, the value of which is uncertain. This initial topic of the new Controversies in Hypertension series highlights important differences among current U.S., European, and Canadian practice guidelines, then moves on to editorial commentaries with different perspectives. [ABSTRACT FROM AUTHOR]